intensive active service to the ultimate aims of all organic processes in that we, where success is achieved, are endowed with the power to intervene, helpfully regulating, where values are endangered, while the purely teleological observers can only lay their hands in their laps, deedless, mourning the disintegration of the whole. Chapter II The Methodology of Biology and Particularly of Ethology 1. The Concept of a System or an Entirety The goal of biologists is, as I have said, to make an

system is indispensable because the learner-listener, exactly as the researcher, can understand the single part, the "subsystem," only when he has also understood all the other parts. From what source, for example, the piston gets the energy that enables it to develop a capacity for suction can first be compre­ hended by the learner after he has understood the functions of all the other parts which provide the flywheel with kinetic energy; he must know why and to what end the camshaft runs half

channel" is the single sentence my friend, Edward Grey Walter, chose to summarize a lecture I once gave on the necessity of repeated observations. One day, after a long period of unconscious data accumulation, the gestalt that has been sought is there, often coming completely unexpect­ edly and like a revelation, but full of the power to convince. The enor­ mous fund of facts that the perceptual mechanism must amass before it is brought to a position to be able to convey such a result plays, in

fatigue of one motor pattern, or of one "set" of motor patterns, is different from fatigue in general with regard to one important point: After general fatigue, the restitution of normal readiness to act reaches a definite level and stops there, while the experimentally enforced quiescence of a fixed motor pattern causes an almost unlimited lowering of the threshold values of releasing stimuli; this makes possible the acceptance as stimuli of inadequate substitute objects. If an experimental

was not at all easy with a mouthbreeding species whose eggs have to be continously whirled about as they normally are by the breathing movements of the mother. Seitz's patience did not flinch before the task of constructing an egg-whirling apparatus consisting of a number of upward directed jets of warm, aerated water on which the eggs were kept dancing. When he had finally succeeded in rearing to full maturity five males which had never seen their own kind, Seitz invited me to watch the crucial